The present invention relates to an electrical connector for use underwater or in a wet or severe environment comprising first and second connector parts adapted to be interengaged to establish an electrical connection. It also relates to a connector part for such a connector.
Electrical connectors for use underwater are known, for example from United Kingdom patent application No. GB-A-2,192,316, to have first and second connector parts in which the first connector part has at least one pin projecting from a support which is inserted into a housing and fixed in place by a retainer ring. The pin has an axially extending conductive copper core surrounded by an insulating sleeve which is arranged to expose an area of the conductive core at or near the tip of the pin for making electrical contact with a contact socket in the second connector part.
The housing extends in an axial direction from the support, radially outwardly of the contact pins, for alignment with and to receive the housing of the second connector part during interengagement. This extended housing of the first connector part defines a pin chamber in which the pins extend.
In the de-mated condition this pin chamber is exposed to the external environment and flooded with, for example, sea water. The insulating sleeve is intended to insulate the conductive core of the pin from exposure to the external environment.
GB-A-2,192,316 discloses an embodiment of a connector having a wiper member provided on a resiliently biased piston for removing contaminants from the outer surface of the pin prior to the entry of the pin into sealed chambers of the second connector part. During connection, the wiper is pushed rearwardly along the pin by the other connector half as it advances. The pin chamber defined by the first connector housing behind the piston reduces in volume during this process. The chamber is connected to the external environment, or “free flooded”, in order to allow the change in volume.
GB-A-2,264,201 discloses an underwater electrical connector having a plurality of pins extending from and supported by a pin carrier and having a pin carrier seal provided at the face of the pin carrier, adjacent to the pins. The contact areas of the pins are electrically isolated from the external environment at all times by way of a slidable and resiliently biased dielectric seal carrier disposed on the pins. The dielectric seal carrier contains an insulating dielectric fluid sealed in a carrier cavity by forward and rearward annular O-ring seals disposed between the pins and the carrier body. The pin chamber, defined by the volume inside the housing behind the dielectric seal carrier and in front of the pin carrier is open to the external environment of seawater, i.e. it is free flooded.
During interengagement with the second connector part, the dielectric seal carrier is pushed rearwardly along the pins compressing the resiliently biased helical spring. The seawater trapped in the pin chamber is allowed to escape to the external environment by a vent hole as the volume of the pin chamber is reduced. When fully mated, a pin protector inner overseal on the rear of the dielectric seal carrier and the pin carrier seal are arranged such that they are energised to expel any seawater from between their joining faces. The purpose of the pin carrier seal is to seal the pin against the outside environment when the connector parts are fully mated.
GB-A-2,330,702 discloses an underwater electrical connector part having a resiliently biased, axially movable shuttle provided between the pins and the housing. The pins are retained in a chamber defined by a membrane containing insulating fluid. In this case, therefore, the pin chamber is not free flooded. The membrane is connected to the axially rearward face of the shuttle and the axially forward face of the pin support and double O-ring seals are provided between the shuttle and the pins to seal the chamber from the external environment. The connector part is flooded with seawater from the external environment radially outwardly of the membrane. The membrane is of a suitable material to allow for pressure balancing in the pin chamber when the shuttle is moved rearwardly against the resilient bias of a helical spring during interengagement of the connectors.
The sealed chamber and shuttle arrangement provides a seal for the base of the pins at all times. However, the movable shuttle and membrane arrangement is a complicated arrangement which provides protection from the external environment to the whole of the length of the pin. This may make the apparatus more prone to failure due to the large number of moving parts and the moving seals.
US-A-2005/0202720 discloses a hermetic pressure connector for providing an electrically conductive connection through a hole in a bulkhead, the connector having a high pressure side and a low pressure side defined by a transverse support member through which extends a plurality of pins supported on a molded connector body. The transverse support member may be made of metal and is provided as a block arranged to seat against a pressure bearing ledge of the bulkhead and abut the bulkhead at its outer diameter. The pins have an insulating sleeve and the molded connector body sealingly engages the transverse support member, the connector pins and the insulating sleeves. The transverse support member offers mechanical support to each of the pins where they protrude from the molded connector body.
GB-A-2,361,365 discloses a high voltage electrical connector comprising a first connector part having pins which are arranged to, during interengagement, pass through a seal of a second connector part into a sealed chamber to make an electrical connection therein. The pins have an axially extending conductive core surrounded by an axially extending insulating portion. When an electrical connection is made and current is flowing, the electrical field gradient can become high in the area proximal to the conductive core such that the equipotential electrical field lines are condensed in the region of the seal of the second connector due to the earthing effect of sea water. This high electrical field gradient subjects the seal to high electrical field stress which, after prolonged use, can lead to degradation and failure of the seal, leakage into the sealed chamber and damage to the second connector part. To reduce this, a screening conductive layer electrode is embedded in the pin arranged to screen the seal of the second chamber from a concentration of equipotential electrical field lines in the mated condition. This embedded screening electrode leads to a connector pin structure which may be difficult to mold.
An alternative known arrangement is to provide a metal screening sleeve embedded in the pin at the pin base and the insulative layer of the pin being formed to have a recess in which the metal screening sleeve is seated so that its outer surface is flush with the outer surface of the insulative layer of the pin forwardly of the sleeve. This structure requires careful molding of the pin.